content: /**
   * Copyright (c) 2016-present, RxJava Contributors.
   *
   * Licensed under the Apache License, Version 2.0 (the "License"); you may not use this file except in
   * compliance with the License. You may obtain a copy of the License at
   *
   * http://www.apache.org/licenses/LICENSE-2.0
   *
   * Unless required by applicable law or agreed to in writing, software distributed under the License is
   * distributed on an "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See
   * the License for the specific language governing permissions and limitations under the License.
   */
  
  package io.reactivex.flowable.internal.operators;
  
  import java.util.concurrent.TimeUnit;
  import java.util.concurrent.atomic.*;
  
  import org.reactivestreams.*;
  
  import hu.akarnokd.reactivestreams.extensions.RelaxedSubscriber;
  import io.reactivex.common.Scheduler;
  import io.reactivex.common.exceptions.MissingBackpressureException;
  import io.reactivex.common.internal.disposables.*;
  import io.reactivex.flowable.Flowable;
  import io.reactivex.flowable.internal.subscriptions.SubscriptionHelper;
  import io.reactivex.flowable.internal.utils.BackpressureHelper;
  import io.reactivex.flowable.subscribers.SerializedSubscriber;
  
  public final class FlowableSampleTimed<T> extends AbstractFlowableWithUpstream<T, T> {
      final long period;
      final TimeUnit unit;
      final Scheduler scheduler;
  
      final boolean emitLast;
  
      public FlowableSampleTimed(Flowable<T> source, long period, TimeUnit unit, Scheduler scheduler, boolean emitLast) {
          super(source);
          this.period = period;
          this.unit = unit;
          this.scheduler = scheduler;
          this.emitLast = emitLast;
      }
  
      @Override
      protected void subscribeActual(Subscriber<? super T> s) {
          SerializedSubscriber<T> serial = new SerializedSubscriber<T>(s);
          if (emitLast) {
              source.subscribe(new SampleTimedEmitLast<T>(serial, period, unit, scheduler));
          } else {
              source.subscribe(new SampleTimedNoLast<T>(serial, period, unit, scheduler));
          }
      }
  
      abstract static class SampleTimedSubscriber<T> extends AtomicReference<T> implements RelaxedSubscriber<T>, Subscription, Runnable {
  
          private static final long serialVersionUID = -3517602651313910099L;
  
          final Subscriber<? super T> actual;
          final long period;
          final TimeUnit unit;
          final Scheduler scheduler;
  
          final AtomicLong requested = new AtomicLong();
  
          final SequentialDisposable timer = new SequentialDisposable();
  
          Subscription s;
  
          SampleTimedSubscriber(Subscriber<? super T> actual, long period, TimeUnit unit, Scheduler scheduler) {
              this.actual = actual;
              this.period = period;
              this.unit = unit;
              this.scheduler = scheduler;
          }
  
          @Override
          public void onSubscribe(Subscription s) {
              if (SubscriptionHelper.validate(this.s, s)) {
                  this.s = s;
                  actual.onSubscribe(this);
                  timer.replace(scheduler.schedulePeriodicallyDirect(this, period, period, unit));
                  s.request(Long.MAX_VALUE);
              }
          }
  
          @Override
          public void onNext(T t) {
              lazySet(t);
          }
  
          @Override
          public void onError(Throwable t) {
              cancelTimer();
              actual.onError(t);
          }
  
          @Override
          public void onComplete() {
              cancelTimer();
              complete();
          }
  
          void cancelTimer() {
              DisposableHelper.dispose(timer);
          }
  
          @Override
          public void request(long n) {
              if (SubscriptionHelper.validate(n)) {
                  BackpressureHelper.add(requested, n);
              }
          }
  
          @Override
          public void cancel() {
              cancelTimer();
              s.cancel();
          }
  
          void emit() {
              T value = getAndSet(null);
              if (value != null) {
                  long r = requested.get();
                  if (r != 0L) {
                      actual.onNext(value);
                      BackpressureHelper.produced(requested, 1);
                  } else {
                      cancel();
                      actual.onError(new MissingBackpressureException("Couldn't emit value due to lack of requests!"));
                  }
              }
          }
  
          abstract void complete();
      }
  
      static final class SampleTimedNoLast<T> extends SampleTimedSubscriber<T> {
  
          private static final long serialVersionUID = -7139995637533111443L;
  
          SampleTimedNoLast(Subscriber<? super T> actual, long period, TimeUnit unit, Scheduler scheduler) {
              super(actual, period, unit, scheduler);
          }
  
          @Override
          void complete() {
              actual.onComplete();
          }
  
          @Override
          public void run() {
              emit();
          }
      }
  
      static final class SampleTimedEmitLast<T> extends SampleTimedSubscriber<T> {
  
          private static final long serialVersionUID = -7139995637533111443L;
  
          final AtomicInteger wip;
  
          SampleTimedEmitLast(Subscriber<? super T> actual, long period, TimeUnit unit, Scheduler scheduler) {
              super(actual, period, unit, scheduler);
              this.wip = new AtomicInteger(1);
          }
  
          @Override
          void complete() {
              emit();
              if (wip.decrementAndGet() == 0) {
                  actual.onComplete();
              }
          }
  
          @Override
          public void run() {
              if (wip.incrementAndGet() == 2) {
                  emit();
                  if (wip.decrementAndGet() == 0) {
                      actual.onComplete();
                  }
              }
          }
      }
  }
  